Berlin 2018 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 51: Networks: From Topology to Dynamics (joint session DY/SOE)
DY 51.4: Vortrag
Mittwoch, 14. März 2018, 16:15–16:30, MA 001
Coarsening dynamics of ferromagnetic granular networks - experiment and simulation — •Pedro A. Sanchez1, Armin Kögel2, Robin Maretzki2, Tom Dumont2, Elena S. Pyanzina3, Sofia S. Kantorovich1, and Reinhard Richter2 — 1Univ. of Vienna, Sensengasse 8, Vienna, 1090, Austria — 2Experimentalphysik 5, Univ. of Bayreuth, 95440 Bayreuth, Germany — 3Federal Univ., Lenin av. 51, Ekaterinburg, 620000, Russia
We investigate the phase separation of a shaken mixture of glass and magnetised steel spheres after a sudden quench of the shaker amplitude. Then transient networks of steel spheres emerge in the experiment. For the developing network we observe an initial regime, where the network incubates, followed by a regime where network structures are elongated and broken, and finally a regime where the structures have relaxed to compact clusters of rounded shapes. This phaenomenology resembles the initial, elastic and hydrodynamic regimes observed by H. Tanaka [J. Phys.: Cond. Mat., 2000] during the viscoelastic phase separation for dynamically asymmetric mixtures of polymers. In order to unveil the three regimes we measure order parameters like the mean number of neighbors and the efficiency.
To eluzidate the origin for a viscoelastic phase separation, we use a simple simulation approach to define the key interactions in the experimental system. This way, we discover that along with dipolar and steric interactions, a central attraction between the magnetised spheres is decisive for the coarsening dynamics. Our simulations show three regimes in the evolution of characteristic order parameters.